Many industries rely on the flexibility and strength of pressure sensitive adhesives (PSAs), but not all adhesives are alike. In decades past, those in need of high-performance PSAs relied on various solvent-based adhesives that dominated the market. The health and environmental dangers of solvent-based adhesives, however, have been recognized since the 1970s, and these products have been under increasing regulatory pressure during the past 30 years or so. Solvent-based adhesives contain binders dissolved in a carrier fluid that contains volatile organic compounds (VOCs). These organic chemicals are emitted into the air during application, curing, and gradually (to a lesser extent) throughout the life of the product. Various compounds in this category have been suspected to cause illness to those exposed directly to them long-term, as well as causing damage to the ozone layer and contributing to the formation of ground-level smog.
Thus the marketplace has demanded other options, and today there are at least two main alternatives to solvent-based PSAs.
Alternative #1: Hot-melt Rubber Adhesives
One alternative to solvent adhesives is 100% solid (no VOC) rubber hot-melt adhesives. These adhesives are 100% solids at room temperature and are liquefied using heat, then applied to a substrate or onto a liner and/or carrier to make PSA tapes.
Hot-melt adhesives have several advantages. Their lack of VOCs eliminates the need for related air quality and environmental precautions during production, application, and disposal. In addition, hot-melt rubber adhesives tend to have a long shelf life, and the application thickness can be closely controlled (solvent- and water-based adhesives can lose 50% or more of their coating thickness during drying.)
They can, however, weather over time when exposed to moisture or chemicals, and they tend to lose bond strength at high temperatures (extremely high temperatures can even re-melt the adhesive).
Alternative #2: UV Cured Low-VOC Acrylic Adhesives
UV cured acrylic adhesives are synthetic, resin-based adhesives suspended in a catalyst of inert organic solvents and then cured via exposure to UV light. This process creates a very strong adhesive product without the concerns over VOC emissions.
UV cured acrylic adhesives tend to be resistant to environmental factors such as sunlight, water, and temperature fluctuation. They’re useful for bonding a wide variety of substrates, depending on the formulation, including plastics, rubber, ceramic, metals, wood, glass, and paper.
The combination of environmental resistance, low-VOC content, and excellent adhesion properties make UV cured acrylic adhesives a good blend of strength and safety for those looking to replace solvent acrylic adhesives in their application.